The study of trends in mortality has been hindered by the changing classifications of causes of death. The changing role of chronic diseases in mortality, for example is largely hidden by the assignment of these deaths to ill-defined or unknown categories. The use of these data requires more than an understanding of changes in medical knowledge. We also need to consider the institutional context in which registration of deaths was developed. The classification of causes of death was sometimes influenced more by governments' needs for information relevant to public health than by prevailing medical theories. This conference will bring demographers and epidemiologists together with historians of medicine to discuss the problems and opportunities in historical studies of causes of death.